The trajectory of the long COVID in the general population of Scotland

In a recent Research Square* preprinted paper under review at Nature WalletResearchers presented results from the nationwide Long Coronavirus Disease (COVID) Scotland Study (Long-CISS) among the general population of Scotland.

Background

Most studies have documented the prevalence of long COVID at any given time. Additionally, studies have measured outcomes in older hospitalized patients with specific conditions (eg, mental health), not the general population. They also lacked a control group to make comparisons.

Additionally, there is a dearth of studies investigating temporal changes in the long COVID. Although it may be a stable condition in some cases, data suggests that it relapses or progresses to a worsened condition in most cases. In some cases, a patient is recovering from a long COVID.

Nonetheless, a better understanding of the magnitude and natural course of long COVID is urgently needed to provide care and support to its growing patient base.

About the study

In the current study, researchers investigated the natural history of long-COVID in the Long-CISS cohort using serial questionnaires completed by enrolled participants at six, 12, and 18 months after the first chain reaction. by positive reverse transcription polymerase (RT-PCR) test.

The Long-CISS study began in May 2021 and recruited eligible participants retrospectively and prospectively. First, the researchers identified eligible adults (>16 years) using the National Health Service (NHS) Scotland notification platform. Then they invited those who had a positive RT-PCR test (as of April 2020) via automated text messages.

Inclusion criteria also required people to complete a six-month follow-up questionnaire plus another questionnaire. Next, they enrolled a comparison group with people who tested negative for COVID-19, matched by age, sex, and deprivation quintile.

Recruited participants also self-reported their recovery status (fully or partially recovered or not recovered) after diagnosis of COVID-19, with the prevalence of its 26 symptoms. Additionally, they provided information on their pre-existing comorbidities and quality of life (QoL). The team calculated the median EQ-5D score of the two study groups at six and 12 months.

Finally, the researchers used McNemar’s tests to compare changes in the prevalence of the 26 Covid-19 symptoms between the two study groups. They ran separate binary logistic regression models for the presence of each symptom at 12 months and repeated them at 18 months.

Study results

Of the 80,332 people diagnosed with symptomatic COVID-19 by RT-PCR, 12,947 and 4,196 completed questionnaires at six- and 12-month and six- and 18-month follow-ups, respectively. The number of people in the control group who completed the questionnaires at the six- and 12-month and six- and 18-month follow-ups were 11,026 and 1,711, respectively.

Regarding recovery status, 41% of the study cohort reported complete recovery at the six and 12 month follow-ups, while 35% reported no recovery, of which 12% reported improvement, but 12% reported deterioration. The 12% whose condition deteriorated between six and 12 months had depression before contracting COVID-19. The six- and 18-month follow-ups revealed a similar trend.

Fortunately, an altered smell, taste, or brain fog symptoms resolved over time. However, after accounting for potential confounders, the COVID-19 group reported having dry cough, productive cough, and hearing problems between six and 18 months of follow-up, which did not resolve. themselves. So, different symptoms drove these different recovery trajectories. Notably, studies have proposed that severe acute respiratory syndrome coronavirus 2 directly invades the ear via angiotensin-converting enzyme 2 (ACE2) receptors. In addition, it triggers hearing loss that may persist.

The study results also revealed that compared to controls, people with symptomatic COVID-19 showed a greater decline in EQ-5D score. Median EQ-5D scores fell from 75 to 74 between six and 12 months of follow-up. It also decreased in controls, from 80 to 77.

Beyond six months after symptomatic COVID-19, people barely reported any changes in recovery status or symptoms. However, 70.7% of people in the study group had at least one persistent symptom, such as fatigue or dyspnea for up to 12 months. The prevalence of these symptoms was also high among people in the comparison group, further highlighting the importance of having a control group.

conclusion

To sum up, the long COVID has emerged as a stable condition in many cases, with many people reporting improvement and deterioration. However, potential confusion could not explain the findings of late-onset cough and hearing problems 12 months after infection. Thus, future studies with longer follow-ups should investigate the underlying reasons for the persistence of long COVID symptoms.

*Important Notice

Research Square publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be considered conclusive, guide clinical practice/health-related behaviors, or treated as established information.